The auction house Sotheby’s said Two Studies for a Self-Portrait (1970) was the finest of all Bacon’s self-portraits and would be sold in New York on 11 May with an estimate of $22m-$30m (£19m-£26m).

Oliver Barker, Sotheby’s senior specialist in international art, described it as “No 1 of all the paintings I’ve handled in my career”.

He added: “Discovering a work such as this is like finding gold dust. To my mind, the painting is worthy of a place alongside the very finest self-portraits of Rembrandt, Van Gogh and Picasso. It’s certainly among the greatest self-portraits ever offered at auction.”

The work shows an almost cheery Bacon and was painted a year before his career-defining retrospective at Paris’s Grand Palais in 1971, that made him only the second living artist after Picasso to have been afforded that honour.

It was also a time, it can be assumed, that things were steady between Bacon and his partner George Dyer. The following year, on the eve of the show, Dyer killed himself – an incident that haunted the artist for decades to come.

Two Studies for a Self-Portrait has been exhibited only twice before. At the 1971 retrospective and in 1993 at Marlborough Fine Art, London.